1. Division of Pulmonology, Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
2. Department of Thoracic and Cardiovascular Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
3. Department of Thoracic and Cardiovascular Surgery, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
4. Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Hospital, Seoul National University College of Medicine, Seoul, Korea.
5. Department of Thoracic and Cardiovascular Surgery, Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea.
6. Department of Pulmonology and Critical Care Medicine, Yangsan Hospital, Pusan National University School of Medicine, Yangsan, Korea.
7. Department of Thoracic and Cardiovascular Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
8. Department of Pulmonology and Critical Care Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.
9. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Samsung Medical Center, School of Medicine, Sungkyunkwan University, Seoul, Korea.